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    <title>Document</title>
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<script>
        
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    var b = 20;
    console.log(a)
    console.log(b)
    console.log(typeof a)
    console.log(typeof b)
    console.log(a - b);
    console.log(typeof (a - b));

    console.log(a);
    console.log(typeof a);

</script>
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